Humpback whale
(Megaptera novaeangliae)

Humpback whales are uncommon in Madeira and are usually observed as single individuals (Freitas et al., 2012; Alves et al., 2018). Records are concentrated in spring and early summer, with confirmed sightings between April and July, while occasional records in September and November suggest that passage may also occur later in the year (Freitas et al., 2012; Alves et al., 2025). Together with photo-identification matches linking Madeira to Cabo Verde breeding grounds and Icelandic feeding grounds, this seasonal pattern supports the interpretation of the archipelago as a crossing point within eastern North Atlantic migratory routes, most likely during northbound passage (Freitas et al., 2012; Alves et al., 2025).

Humpback whales are acoustically characterized mainly by complex songs produced by males, composed of stereotyped units arranged hierarchically into phrases, themes and full songs (Payne and McVay, 1971). These vocalizations typically occupy a broad band from ~50 Hz to 4 kHz, with many units concentrated below 2 kHz, and songs usually last about 7–30 min before being repeated in extended singing bouts (Au et al., 2006). In addition to song, humpback whales produce a broader repertoire of non-song social sounds, most with fundamental frequencies below 3 kHz, although the full reported range extends from 50 Hz to 24 kHz depending on call type (Recalde-Salas et al., 2020). However, song remains the most distinctive signal and the most useful for tracking seasonal acoustic presence. In the eastern North Atlantic, humpback whale song has been recorded on the Cape Verde breeding grounds during spring, consistent with breeding associated acoustic activity in that region (Ryan et al., 2019; Wenzel et al., 2020).